Maximum-stress control lever



Oct. 30, 1962 H. J. NEUFr-:LD ETAL 3,060,763

MAXIMUM-STRESS CONTROL LEVER Filed Nov. 14, 1960 ,VN mm NN H -Lmn r Il ...E

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United States Patent O Mice 319093 3,060,763 MAmUM-STRESS CGNTRQI. LEVER Henry J. Neufeld and Jake J. Neufeld, both of Box 122, Horndeau, Manitoba, Canada Filed Nov. 14, 1960, Ser. No. 69,032 8 Claims. (Cl. 74-524) The present invention relates to a maximum-stress control lever for use with heavy equipment. The invention relates particularly to a control mechanism used to actuate equipment which is operated by cables, such as earth Scrapers, earth loaders, cranes, etc.

It is an object of the invention to provide a control lever which automatically prevents undue stress being applied to cables during operation of heavy equipment, particularly to automatically prevent cable breakage resulting from overload.

it is a further object to provide an automatic maximum-stress control lever which combines electro-magnetic means and a member having limited resilience, to automatically release the control when a predetermined maximum-stress has been reached.

A still further object is to provide maximum-stress control lever comprising in combination: handle means, a rigid jacket extending from end of said handle means, a resilient insert associated with said lever permitting limited bending thereof under maximum-stress, a trigger plate pivotally attached to said jacket at the end opposite said handle means, latch means within said jacket normally holding said trigger plate and said jacket in rigid relationship, normally open electrical contact means within said jacket, said contact means between said tension bar and said electrical contact being adapted to close when maximum-stress is applied to said lever, electromagnetic means Within said jacket associated with said latch means and said contact means and adapted to release said latch means when said contact means are closed.

In the past operators of heavy equipment such as earth Scrapers have encountered considerable difficulty in preventing breakage of the operating cables due to inadvertent overload.

Such equipment is commonly operated by hydraulic motors of relatively unlimited power, .and when overloading is encountered the power of the motor is suiiicient to strain the operating cables to the breaking point. The operating cables are normally connected to the source of power via a clutch which is engaged by means of a manually controlled lever.

The present invention overcomes the problem of cable breakage, and thus eliminates the expense of replacement cables and lost time during cable replacement, by providing a controllever which automatically disengages the cable from the power drive before maximum-stress has been applied to the cable.

A detailed description of the invention will now be made with reference to the accompanying drawings in which:

FIGURE l is a plan view of the lever according to the invention;

FIGURE 2 is a cross section along line A-A of FIG- URE l;

FGURE 3 is a fragmentary view of a section of the lever shown in FiGURE 2 illustrating the control lever in release.

In the plan view of FIGURE l a jacket 1 housing the control components is provided with integral stubs 2 and 3 projecting from one end thereof and adapted to receive a primary axle 4. Trigger plate 5 is pivotally attached by axle 4 between stubs 2 and 3. Handle 6 is bolted to the end of jacket 1 opposite trigger plate 5 by bolts 7 and 8 embedded in shaft 9 which is threaded to receive said bolts 7 and 8.

Patented oet. ao, 1962 A hard rubber resilient insert 10 is held between top plate 11 of jacket 1 and bottom plate 12 of handle 6 by bolts 7 and 8. Top plate 12 may be Welded or otherwise be iixedly attached to handle 6.

Referring to FIGURE 2 solenoid 13 is enclosed within solenoid jacket 14 and is attached to a power source at its top end by lead 1.5 through a relay 31, which has three terminals and is similar to a switch of the type used on cars with a push button starter. Solenoid jacket 14 is positioned within jacket 1 so as to rest on the bottom lip 16 of jacket 1 and at the opposite end is held in a xed position within jacket 1 by restraining finger 17 or by any other suitable means. The electrical circuit also includes contact bar 1S iixedly attached to bottom plate 12 of handle 6. Contact 19 is mounted on the wall of jacket 1 by the lock nut 20 and connected by lead 21 to a heavy terminal of the relay 3l. In the switch used on cars, one of the terminals is for the battery cable, another is for the starter cable, and a third and smaller terminal is for the push button wire. ln using the relay or switch for the control lever according to the invention, the lead from the battery is connected to one heavy terminal, lead 15 is connected to another heavy terminal and lead 21 is connected to the smaller terminal on the relay. Contacts 18 and 19 are positioned to cooperate in closing the electrical circuit of solenoid 13. Magnetic core 22 within solenoid 13 supports movable latch 23 which is seated in a suitable latch well 24 provided in trigger plate 5. Circuit breaking contact points 25 are mounted on top of solenoid 13 and circuit breaker 26 projects upwardly from magnetic core 22. Drive cable attachment means 27 are provided at lower end of trigger plate 5.

Referring now to FiGURE 3 which shows the latch 23 released from latch well 24, magnetic core 22 is shown elevated within solenoid 13, circuit breaker 26 is holding circuit breaking contact points 25 in open position and trigger plate S is pivoted on `axle 4 relative to jacket 1.

Earth Scrapers and movers are operated by cable connections, and because of overload and careless operation, cable breakage is quite common. The cable lifters on such equipment are operated -by levers, which actuate friction clutches and as the operator pulls the operating levers a friction clutch is engaged and the earth mover is loaded or dumped. In event of an 4overload the operator can, by applying too much pressure to the lever snap the cable. However, by means of a safety device within the control lever, cable breakage is eliminated.

In ordinary operation the operator moves said handle 6 in the direction of arrow 28, thus pivoting the lever on axle 4 and the cable attachment 27 is driven in the direction of arrow 29. When excess pressure is applied by the operator to the cable attached at 27 not shown, the safety control within said lever will react to release latch 23 and permit jacket 1 and handle 6 to pivot freely on stubs 2 and 3 and main axle 4. v

Initially the control lever is adjusted with a predetermined tension by adjusting said adjustable contact 19 to the desired gap between contacts 18 and 19 and by tightening bolts 7 and 8 to suitably limit the resilience of hard rubber insert 10. In this way the operator may transport any load within the means of the tension that the cable can endure; thus the safety mechanism will only come into play when overloading is encountered. In event of an overload as the operator moves said handle 6 in the direction of arrow 28, thus pivoting the entire lever on axle 4 and pulling cable attachment means 27 in the direction of arrow 29, the resistance encountered by the clutch cable causes said resilient insert 10 to give slightly, thereby forcing contact bar 18 toward contact 19 until contact is made. Thus when contacts 18 and 19 meet, an electrical circuit which engages a relay, is completed. This said relay closes a circuit to supply electrical current to lead 3 15, thus completing the circuit for solenoid 13 which is grounded throughout the frame 4of the mechanism. At this instant, solenoid 13 is actuated, producing an electromagnetic force which elevates said magnetic core 22 and in doing so releases said latchV 23 from said latch well 24. The release of said latch mechanism causes the lever in eiect to break at said main pivot at primary axle 4, said trigger plate 5 is no longer controlled by handle 6 and the cable tension is relaxed. Almost simultaneous with said solenoid 13 actuation, said circuit breaker 26 projects upward and disrupts the complete circuit by breaking contact between said contact points 25, thus permitting magnetic core 22 and latch 23 to drop toward trigger plate 5. It may also be pointed out that a limit of travel switch is neverthelessV extremely important in the dumping operation.

This limit of travel switch is an integral part of the dumping apparatus in heavy cable-operated equipment such as earth Scrapers, earth loaders, movers etc. and it performs a similar function to contact 19, that of engaging a relay, completing an electrical circuit and thus triggering the lever.

In FIGURE 2, the limit of travel switch is designated by 30 Iwhich is connected to the small ter-minal on the relay, which is in turn connected to lead 21. Initially, the limit of travel switch is engaged when the ejector of the `dumping apparatus moves -forward to a certain point of travel. WhenV this distance has been reached said switch which consists of an insulated flat spring mounted stationary with a Wire leading to a relay is grounded by the moving part of the dumping or lifting 4mechanism of the machine, the circuit being completed to the relay and in doing so triggers said lever repeating the automatic control activation described previously.

The lever may then be instantly reset by the operator by simply pushing the handle 6 in the direction opposite that of arrow 28. As the handle 6 and jacket 1 are pivoted back into alignment with trigger plate 5, latch 23 will slide lalong the upper surface of trigger plate 5 until it drops into latch vwell 24, to lock the lever for re-use.

In practice the automatic release and re-setting of the lever is accomplished in seconds. The operator is free to quickly determine the presence of overload by making several attempts in quick succession to actuate his machine without fear of cable breakage.

The foregoing disclosure is the best mode known to implement the invention, but is by way of example only, and the invention is to be limited only -by the scope of the accompanying claims.

The embodiments :of theinvention in which an exclusive property or privilege is claimed are defined as follows:

1. Maximum-stress control lever comprising in combination: handlemeans, a rigid jacket extending from one end of said handle means, a resilient insert associated with 'said lever permitting limited bending thereof under maximum-stress a trigger plate pivotally attached'to said jacket at the end opposite said handle means, a latch within said jacket normallyV holding said trigger plate and said jacket in rigid relationship, normally open electrical contact means within said jacket, said contact means being adapt- 4 ed to close when maximum-stress is applied to said lever, electromagnetic means within said jacket associated with said latch means and said contact means and adapted to release said latch when said contact means are closed.

2. Maximum-stress control lever according to claim 1, said resilient insert 'being composed of hard slightly compressible material and being iixedly held between said jacket and said handle by bolts, saidbolts beingadapted to be tightened on said insert to adjust the resiliency thereof. 3. Maximum-stress control lever according to claim 1, said contact means comprising a rst contact mounted on the wall of said jacket, a second contact aixed to the underside of said handle and Vprojecting through said resilient insert into said jacket, said first and second contacts having a gap therebetween which is adapted to be closed when maximum-stress is applied to said resilient inert, said first contact being adjustably mounted on the Wall of said jacket to permit adjustment in the length of said gap.

4. Maximum-stress control lever according to claim 1, said electromagnetic means comprising a solenoid, an electromagnetic core within said solenoid, a latch depending frorn said core, said solenoid acting to elevate said core and said latch when said solenoid is connected to a source of electricity.

5. Maximum-stress lever according to claim 4, said solenoid having normally closed circuit breaking contacts mounted on the uppersurtface thereof, a circuit breaker projecting upwardly from said core adapted to open said circuit breaking contacts when said core is elevated within said solenoid.

6. Maximum-stress lever accordingto'claim 1, a solenoid within said jacket, an electromagnet vertical core within said solenoid, said latch being pivotally suspended from the bottom of said core, said trigger plate being pivotally attached to stubs xedly attached to the end of said jacket adjacent said latch, a latch well in said trigger plate adapted to receive said latch when said solenoid is not connected to a source of electricity.

7. Maximum-stress lever accordingY to claim 1, said jacket having downwardly projecting stubs iixedly attached thereto, a main axle pivotally supporting said stubs and the entire lever, a trigger plate pivotally mounted on said main axle, cable attachment means at the `end of said trigger plate remote from said jacket, a solenoid within said jacket, a magnetic core within said solenoid, said latch being pivotally suspended from the bottom of said core, a latch Well in the upper surface of said trigger plate normally cooperating Withsaid latch to lock said trigger plate to said jacket.

8. Maximum-stress control lever according to claim l, said contact means including a control means acting similarly but independently of said electrical contact means within said jacket and positioned externally.

References Cited in the le of this patent UNITED STATES PATENTS 2,881,636 Palmleaf Apr. 14, 1959 

